1. Field of the Invention
The present invention relates to a substrate treatment method and a substrate treatment apparatus and, more specifically, to a substrate treatment method of applying a coating solution to a substrate, for example, a semiconductor wafer, an LCD substrate and the like to form a coating film on the front surface of the substrate and an apparatus therefor.
2. Description of the Related Art
Conventionally, a technology of forming multilayer wiring on the substrate is employed with an increase in integration of semiconductor devices, in which a silicon oxide film-based glass that is referred to as SOG (Spin On Glass) is used as a film for insulating wirings in the multilayer wiring, that is, circuit patterns from each other.
The method of forming the SOG film is generally a method of applying a glass component molten in an organic solvent onto the substrate by a spin-coat method, and drying and burning it by thermal treatment such as baking or curing to bond the glass component thereto, thus forming a film.
However, a circuit pattern with projections and depressions is formed on the front surface of the substrate, and therefore when a typical spin coating method and thermal drying are performed, unevenness in shape of the film surface following the shape of level differences of the projections and depressions occurs, causing problems in subsequent process steps. The problems are, for example, that for lithography, if performed, various poor conditions are caused, such as degradation in line width (CD) due to an increased focal depth, an increase in level difference with stacking of films and so on.
Hence, there is a need to flatten the coating film. As the method of flattening the coating film, a chemical mechanical polishing (CMP) technology is known in which after the coating film is cured by thermal treatment, a polishing solution containing mechanical polishing particles and chemical polishing particles is then dropped onto the surface of a polishing cloth being a polishing member, and the surface of the polishing cloth is pressed against the coating film on the substrate to remove a part of the coating film.
Besides, as another flattening method without undergoing the high-load process such as CMP, a coating method and apparatus are known in which a coating solution is supplied to the substrate surface having an uneven surface so that a coating film is spread out to be thin over the surface of the substrate by a scanner plate, and an air pressure from a nozzle in a slit form is used to evenly press it (see Claims and FIG. 1, FIG. 2, and FIG. 4 in Japanese Patent Application Laid-open No. Hei 7-47324). As still another means, a coating method and apparatus are known in which a coating solution is supplied to the surface of the substrate, a gas containing a solvent vapor is then supplied to thereby make the coating film thin and even (see paragraph number 0142 and FIG. 8 and FIG. 13 in Japanese Patent Application Laid-open No. Hei 11-329938).